Vapor discharge lamp



D. s. GUSTIN VAPOR DISCHARGE LAMP Filed July 5, 1957 Oct. 24,1939.

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I V I4 1 l P 2, z a d INVENTOR i. J. Gaff/(V.

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ATTORNEY Patented Oct. 24, 1939 PATENT OFFICE VAPOR DISCHARGE LAMP Daniel S. Gustin, Bloomfield, N. J., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa, a corporation of 1 Pennsylvania Application July 3, 1937, Serial No. 151,817

6 Claims.

This invention relates to discharge lamps wherein an electric discharge occurs between two electrodes in an ionizable medium and has particular reference to alamp of this type which is self-contained.

In lamps of this character, the life thereof is more or less dependent upon the life of the electrodes. Since the spacing of the electrodes is relatively great thus causing the lamp to have a high resistance, a high voltage would be required to initiate a discharge unless the high voltage is in some manner compensated for. If a high voltage is applied, sufiicient to initiate, a discharge, the electrode, momentarily functioning as the cathode, will sputter, shortening its useful life and naturally that of the lamp. Also, when the voltage is applied before the cathode reaches a temperature to freely emit electrons, the discharge is usually concentrated. at one spot which,

due to ion bombardment, overheats such spot again shortening the life of the lamp.

For the purpose of controlling the amount of current supplied to a lamp of this type it has been customary to employ auxiliary starting equipment such as an impedance or the like connected in series with the electrodes of the tube. Inasmuch as such equipment is of a cumbersome nature, the necessity therefor has to a great extent retarded the adaptation of such lamps to domestic lighting for homes and the like.

It-is accordingly an object of the present in,- vention to provide a gaseous discharge lampwhich is operable directly from the usual source of commercial voltage.

Another object of the present invention is the provision of a "gaseous discharge lamp requiring no cumbersome auxiliary equipment to initiate a discharge.

Another object of the present invention is the provision of a gaseous discharge lamp provided with internal means for-limiting the current supplied to the lamp and which at the same time heats the electrodesjto an electron emitting temperature.

A further object of the present invention is theprovision of .a self-contained gaseous discharge lamp having an impedance forming an integral part of the lamp serving to limit the current and at the same time being operable to heat the electrodes to an electron-emitting temperature, and, in addition, such self-contained lamp is provided with an internal device for initially ionizing the gas within the envelope and causing a discharge between the operating electrodes.

Still further objects of the present invention 1 although this is not essential, and having a cylinfication of construction which the electrode end of the tube may take, and

Fig. 5 is an elevational view of a portion of the modified construction shown in Fig. 4. 15

Referring now to the several figures in detail, the lamp shown in Fig. 1 may comprise a vitreous envelope 5 which, after evacuation, is filled with a metallic vaporizable material, such as mercury, sodium, or the like, or a gaseous environment such as helium, hydrogen, neon, argon, or the like, either alone or in combination with the metallic vaporizable material.

As shown in Figs. 1, 2, and 3, the ends of the tubular envelope may be closed by a metallic closure member 6, of suitable alloy steel and sealed to the envelope to form a vacuum-tight connection, such as by'a feather edge 1, if desired,

drical portion 8 closed at one end and forming re entrant stems for the lamp.

An electrode 9 of refractory metal, such as tungsten, which may be coated with an electronemitting material, as is well known in the art, has one of its ends welded or otherwise aifixed to the metallic reentrant portion 8 while its remaining end is similarly secured to a metallic collar or the like Hi. This metallic collar is suitably insulated from the reentrant stem 8 by an insulating collar I2 and supports a bi-metallic thermostatic strip l3 (see Fig. 3) as well as an insulated conductor l4 extending internally of the envelope which initially interconnects the electrodes. Contact is established with the conductor M by a projection l5 on the bi-metallic strip I 3 engaging an exposed portion of the conductor M at each end, as can be seen in Figs. 1 and 2.

For the purpose of heating the electrodes 9 to an electron-emitting temperature, as well as to heat the bi-metallic strips l3 and at the same time limit the amount of current supplied to the lamp, an impedance, such as a resistance I6, is provided which forms an integral part of the lamp. Since such resistance element isdisposed at each end ment. In order to connect this resistance element in series with the electrode and the source of electrical energy Ll, L2, one end of the winding I8 is connected to the metallic reentrant stem 8 through the medium of a conductor which extends upwardly of the reentrant stem and :is secured near the base by welding or soldering to facilitate assembly.

Each end of the lamp may be provided with an insulated base 22 cemented to the envelope and having a metallic thimble 23 crimped around an annular projecting portion of the base 22. To complete the circuit from the source through the resistance element to the electrode, the re maining end of the resistance is connected. by a conductor 24 which is soldered or otherwise affixed to the metallic thimble 23.

When current is supplied to thelamp, it passes through the thimble 23 and conductor 24 to the winding 18 and thence through reentrant stem 8 to electrode 9, metallic collar I9, bi-metallic strip l3, and conductor l4 to the other electrode, thus connecting both resistances, bi-metallic strip, and electrodes in series with the source LI; L2. The passage of current accordingly causes the resistance element IE to heat up and heat the electrode 9 to electron emitting temperature, as well as the bi-metallic strip l3. Upon the thermostatic strip l3 being heated to an appropriate temperature, it will flex in the manner shown in full lines in Figs. 1 and 2, thus breaking the connection between the tip I5 and the conductor l4.

Despite the fact that current is flowing simultaneously through both resistance elements and they heat the respective juxtapositioned thermostatic elements, it is nearly impossible to have both thermostatic elements. break their connection at precisely the same instant. Accordingly, upon the opening of the thermostatic strip I3, an arc will first be initiated between the exposed portion of the conductor l4 and the electrode 9 functioning as cathode. This will initially ionize the gas within the lamp, thus facilitating the striking of an arc between the electrodes 9 when the other bi-metallic strip opens.

After the opening of both thermostats l3, current flows entirely through the resulting arc since the conductor I4 is completely opened at both ends. The current supplied to the lamp,h0wever, is limited by the integral resistance elements 16, both of which remain permanently connected in series with the electrodes. Accordingly, the resistance elements may be made any desired valueso as .to give the lamp a preselected wattage. For example, the lamp may be designed to operate on volts at a total of 25 watts, and eachresistance given a valuesuch as to consume 5 watts of energy, leaving a total of 15 Watts for light emission, or any other desired proportion.

In Figs. 4 and 5, a modification of the device is shown wherein the resistance elements l6, although in operation forming an integral part of the lamp, may be removed for replacement or repair. To this end the metallic reentrant stem portion 8 is provided with coarse threads or the like 25 and the seal 1 is of smaller diameter and is sealed to a small annular portion 26 formed on a closure member 21. This closure member may then be fused at 28 to the tubular portion of the envelope 5 to facilitate assembly of the parts.

The base in this instance may consist of an insulating collar portion 29 of sufiicient diameter to surround the annular portion 25 and the metallic thimble 23, both of which are rigidly secured to the core ll of the resistance element IS. The conductor 24 extends through a bore 30 provided in the core and again connects to one rigidly secured to the core I1 which is provided with threads of the same diameter and pitch) as that of the metallic reentrant stem portion 25. In all other respects the construction and elements, such as the electrodes and thermostats, are identical to the modification previously described.

' end of the winding I8 while the other end of the winding I8 is connected to a metallic shell 32' thimble 23 and the shell 32, the engagement of the unit with the reentrant portion 8. immediately completes an electrical connection to the electrode 9 and to the bi-metallic strip l3. Also,

.since the reentrant portion is sealed to the closupplied to the lamp so that it may be operated directly from electrical supply sources of the usual commercial voltage without the necessity for cumbersome auxiliary equipment. Moreover, the resistance element also functions as a heater for the purpose of initially heating the electrodes to an electron-emitting temperature, and at the same time serves to cause operation of a thermostatic element for breaking the circult and. initiating the arc.

Although two modifications of the invention have been shown and described, it is to be understood that other embodiments thereof may be -made without departing from the spirit and scope of the appended. claims.

I claim: 1. A gaseous discharge lamp comprising a vitreous envelope provided with at least one reentrant stem, said stem having a portion thereof of heat conducting material. an ionizable me-- dium within said envelope, electrodes within said envelope adapted to sustain an arc therebetween during operation of said lamp, and means disposed interiorly of said reentrant stem and electrically connected toat least one of said electrodes, said means being disposed in close prox-.

imity to said heat conducting portion of said 75 I reentrant stem and to said electrode and conentrant stem having a metallic portion, an

ionizable medium within said envelope, electrodes within said envelope adapted to sustain an arc therebetween during operation of said lamp, and means disposed interiorly or said reentrant stem in contact with the metallicportion thereof and in juxtaposition to at least one of said elec trodes for heating said electrode to an electronemitting temperature and for limiting the current supplied to said lamp during operation.

3. A gaseous discharge lamp comprising" a vitreous envelope provided with at least one reentrant stem and containing an ionizable medium therein, electrodes within said envelope adapted to sustain an arc therebetween during operatlonoi' said lamp, heat responsive means disposed interiorly of said lamp adjacent said reentrant stem and operable to initially cause ionization of said medium to facilitate the starting of the discharge between said electrodes, and means disposed interiorly of at least one of said reentrant stems in juxtaposition to said heat responsive means and one electrode for heating said electrode to an electron-emitting temperature as well as heating said heat-responsive means, to cause the formation of an are within said lamp, and for limiting the electrical current supplied to said lamp during operation.

4. A gaseous discharge lamp comprising a dium therein, electrodes within said envelope adapted to sustain an arc therebetween during operation of said lamp, and detachable means adapted to be rigidly secured to said envelope interlorly of said reentrant stem and electrically connected to said electrode, and said means being I operable to heat at least one of said electrodes to an electron-emitting temperature and to limit the current supplied to said lamp during operation.

5. A gaseous discharge lamp I comprising a vitreous envelope provided with at least one reentrant stem and containing an ionizable medium therein, electrodes within said envelope adapted to sustain an arc therebetween during operation 01' said lamp, heat responsive means disposed interiorly of said lamp adjacentlsaid reentrant stem and operable to initially cause ionization of said medium to facilitate the starting or a'discharge between said electrodes, and detachable means rigidly secured to said envelope interiorly o1 saidreentrant stem and operable to heat at least one of said electrodes to an electron-emitting temperature and to limit the current supplied to said lamp during operation.

6. A gaseous discharge lamp comprising a vitreous envelope provided with at least one reentrant stem and containing an ionizable medium therein, electrodes within said envelope adapted to sustain an arc therebetween during operation of said lamp, and a detachable base for said lamp including an electrode terminal and an integral resistance element adapted to be positioned interiorly of said reentrant stem and electrically connected to at least one of said electrodes for heating said electrode to an electron-emitting temperature, and for limiting the current supplied to said lamp during operation.

DANIEL S. GUSTIN. 

